Technological Properties Of Milk Research Articles

THE INFLUENCE OF THE KAPPA-CASEIN GENOTYPE ON THE NUTRITIONAL VALUE OF MILK

The nutritional property of milk depends on its chemical composition and a high degree of digestibility (95-98%) of all organic substances. The composition of milk includes more than 200 components that are complex in chemical structure, many of which nature has not repeated in any other products. Milk protein, fat and lactose are the main components that directly affect the taste and technological properties of milk. The actual content of the main components in commercial milk can vary in wide ranges: protein from 2.8 to 3.6%, fat from 2.8 to 6%, lactose from 4.5 to 4.8%. To determine the polymorphism of kappa-casein genes and evaluate economically useful traits in animals with different genotypes of kappa-casein, only 60 cows were selected, including 20 Holstein cows, 20 Alatau cows and 20 black-and-white cows. The polymorphism of kappa-casein genes was evaluated by PCR analysis. For further research, 3 subgroups of cows were formed in each group according to the principle of analogues, the results of genotyping and kappa-casein gene. The first group included cows with the AA kappa-casein genotype, the second – the AB genotype, and the third – the BB genotype.

Technology of meat and dairy products enriched with whey protein concentrate

This article presents improved technologies for the production of meat and dairy products, from goat milk and goat meat, using whey. The purpose of the research is to develop the technology and component composition of soft cheese and low - calorie sausage products enriched with whey protein concentrate. The scientific novelty of the project is to conduct experimental studies to study the chemical composition and technological properties of milk and meat of goats of indigenous breeds of the Pavlodar region and milk of imported goats of the Zaanensky and Gorky breeds. The enzyme preparation and its concentration, which provides the necessary density and viscosity of the resulting protein clot, are also justified and selected. A new method of enriching a meat product with whey proteins has been developed, which forms the appearance and appearance on the slice of a new type of sausage made from goat meat of indigenous breeds. The practical significance of the work lies in the development and optimization of the formulation and improvement of the technological process for the production of new types of meat and dairy products, from goat milk and goat meat, increased nutritional and biological value using whey. During the implementation of the research project for the development of the formulation of soft cheese from goat's milk and sausage product from goat meat, theoretical and experimental studies were carried out on the selection and justification of functional components (protein concentrates from secondary dairy raw materials). Formulations of new types of soft cheese and sausage products with a long shelf life, enriched with whey concentrate, have been tested in the laboratory conditions of the Department of Biotechnology of the NAO Toraigyrov University, as well as their storage capacity has been determined as a result of the conducted studies. In addition, qualitative (organoleptic, physico–chemical, microbiological) indicators of prototypes of finished products were determined.

Milk quality of Italian Mediterranean Buffalo as affected by Temperature-Humidity Index during late spring and summer

Eighteen Italian Mediterranean buffalo cows were subjected to fortnightly milk sampling from May to July 2022. Air temperature and relative humidity were monitored throughout the trial; temperature-humidity index (THI) was calculated and ranged from 69 to 79 so that 3 classes were set to study the effect of different THI on milk quality: THI less than 72 - THI < 72; THI ranging from 72 to 76 THI72-76, and THI over 76 - THI > 76. Individual milk samples from buffalo cows were analyzed for milk composition and coagulation traits, fatty acid and amino-acid composition, enzymatic and mineral profile. The THI > 76 class registered the highest lactose content and poorer milk clot characteristics in comparison with THI < 72. Exposure to THI over 76 resulted in increased contents of saturated and short- chain fatty acids in milk as well as in the highest values of atherogenic and thrombogenic indexes and the lowest essential amino-acid content. Moreover, the lowest value of Calcium, Copper and Selenium contents were found in the milk of buffalo cows exposed to THI over 72. Results confirm that Italian Mediterranean buffalo expresses a good level of thermo-tolerance, even though exposure to daily THI over 76 has a deleterious effect on some nutritional and technological properties of milk.

Влияние пробиотиков на молочную продуктивность и технологические свойства молока коз зааненской породы

The article presents the results of experimental studies to study the effect of feeding probiotic feed additives Kluver Pro and BeneFIT Basic on milk productivity, composition and technological properties of milk from Saanen goats. It has been established that feeding probiotics Kluver Pro and BeneFIT Basic as part of the diets of lactating goats of the Saanen breed helps to increase milk yield by 9,5‑4,4% (p≤0,001), the mass fraction of fat in milk - by 0,73% (p≤0,05) and 0,11%, mass fraction of protein in milk - by 0,25% (p≤0,05) and 0,19%, as well as milk clotting time - by 7,3% and 5,4% (p≤0,001) and the formation of a denser rennet curd, which is a desirable property in the production of fermented milk products and cheese making

Morphological justification of the risk of mastopathy in cattle

Mastopathy, as it is known, is one of the fundamental reasons for the decrease in dairy productivity of cows, sanitary and technological properties of milk, as well as premature culling of animals. The purpose of this study was to present a morphological justification of the risk of mastopathy in cattle. The research was carried out on the basis of the Department of Anatomy and Histology of Animals named after Professor Alexey Filipovich Klimov of the Moscow State Academy of Veterinary Medicine and Biotechnology – MBA named after K. I. Scriabin" and the breeding plant "Povadino" of the Moscow region. The object was Holstein cows. To conduct the study, an experimental group of animals (n=102) was selected from a herd of 1200 heads according to the principle of analogues, taking into account breed, body weight, age, number of lactations, reproduction index, which included clinically healthy animals (n=51, control) and experimental animals (n=51, mastitis). A comprehensive methodological approach was used, including a visual assessment of the state of the somatic systems of the animal body, macroscopic morphometry in order to determine the type of their constitution, the somatotype index and linear indicators of the mammary gland. Based on the conducted studies, anatomical and echographic parallels of the state of the mammary gland in the studied animals were established. In cows with mastitis, an increase in the circumference of the gland in comparison with the control group is accompanied by destructive changes in its excretory system in the form of massive fibrin overlays in the area of milk passages represented by heteroechogenic sites.The results obtained are basic in improving the methods of diagnosis and prevention of breast pathologies in cattle.

Review: genetic background of milk fatty acid synthesis in bovines.

Milk fat composition is an important trait for the dairy industry as it directly influences the nutritional and technological properties of milk and other dairy products. The synthesis of milk fat is a complex process regulated by a network of genes. Thus, understanding the genetic variation and molecular mechanisms regulating milk fat synthesis will help to improve the nutritional quality of dairy products. In this review, we provide an overview of milk fat synthesis in bovines along with the candidate genes involved in the pathway. We also discuss de novo synthesis of fatty acids (ACSS, ACACA, FASN), uptake of FAs (FATP, FAT, LPL), intracellular activation and channelling of FAs (ACSL, FABP), elongation (EVOLV6), desaturation (SCD, FADS), formation of triglycerides (GPAM, AGPAT, LIPIN, DGAT), and milk lipid secretion (BTN1A1, XDH, PLIN2). The genetic variability of individual fatty acids will help to develop selection strategies for obtaining a healthier milk fat profile in bovines. Thus, this review will offer a potential understanding of the molecular mechanisms that regulate milk fat synthesis in bovines.

CSN1S1 and LALBA Polymorphisms and Other Factors Influencing Yield, Composition, Somatic Cell Score, and Technological Properties of Cow's Milk.

We evaluated the influence of CSN1S1 and LALBA polymorphisms on cow's milk yield and quality. The analysis was done on Czech Simmental and Holstein cows. Non-genetic factors were included as well. CSN1S1 did not influence the milk performance in the first lactation. In the second lactation, cows with the BB genotype had significantly higher milk, protein, and fat yields than BC. The differences between LALBA genotypes were non-significant in the first lactation, while in the second lactation, the fat percentage was significantly higher in BB than in AB. The farm significantly influenced milk, protein, and fat yields in both the first and second lactations and fat percentage in the first lactation. The effect of CSN1S1 and LALBA genotypes on the milk technological quality was non-significant. Breed did not influence any of the evaluated technological traits and SCS. The ethanol test was not influenced by farm, season, lactation phase, protein percentage, breed, or non-fat solids percentage. Farm, season, and protein percentage significantly influenced milk fermentation ability, renneting, and SCS. The lactose content is a good indicator of udder health.

Evaluation of the technological properties of cowsʼ milk depending on the season of the year

Relevance. One of the main products for consumption and food production in Russia is milk. Its composition is influenced by many factors, including the seasonality of production. In some seasons of the year, milk supplies (both quantitatively and qualitatively) are quite unstable, which creates significant problems for technologists to produce the planned amount of dairy products and forces them to periodically rebuild their operating modes with an inevitable decrease in its efficiency and profitability. In this regard, the study of the influence of the season on the technological properties of cowʼs milk is relevant and has practical significance.Results. As a result of the research, it was found that despite the fact that the conditions for the preparation and processing of cream were similar for milk in all seasons of the year, there were significant differences in the technological properties of milk. Cream was churned faster in spring and summer — in 38 min. and 40 min., and in autumn and winter the duration of churning cream ranged from 49 min. to 63 min. accordingly. The milk of cows in summer was distinguished by the best rate of coagulation under the action of rennet enzyme. The total duration of milk coagulation in this season of the year was less than in other seasons by 5'20''–7'20'' (p &lt; 0.001). The highest milk costs per 1 kg of butter were in spring and summer. According to the ratio of the components of milk when choosing it for cheese making, the best milk was obtained in the autumn-winter period, when the optimal content of SOMO, fat and protein was observed. This is explained primarily by the fact that during this period a large number of animals lactated in the second half of lactation after separation.

Metabolism, productivity and technological properties of milk in cows when using the feed additive BioPrimum dry

Complete feeding of highly productive cows should be carried out with the use of biologically active feed additives, which is the main criterion for obtaining maximum milk productivity. Therefore, it is necessary to introduce optimal dosages of multicomponent feed additives into production, which contribute to increasing productivity and reducing the cost of production. The purpose of the work was to study the metabolism, productivity and technological properties of milk in cows when using the feed additive BioPrimum dry. The research was carried out under the production conditions of OOO “Agrosoyuz” in the Ruzaevsky municipal area in the Republic of Mordovia. The paper scientifically substantiates the possibility of using a new feed additive BioPrimum dry in the rations of cows of Red-and-White. Its optimal dosage has been established and the eff ect on the digestibility of nutrients and the use of mineral elements of the ration, the biochemical status of blood, dairy productivity of cows has been studied. The economic effi ciency of the use of the feed additive BioPrimum dry in cow feeding has been determined. The optimal dosage of the feed additive BioPrimum dry in the amount of 75 mg/ kg of dry matter in cow feeding has been established. Based on the results of production testing, the economic effi ciency of using the tested additive was calculated. The best indicators turned out to be in the cows of the experimental group, when converting the milk obtained to the basic fat content 517,8 kg or 5,8 % higher more milk was received from them. Revenue from sales amounted to 198 124,5 rubles or 10 874,5 rubles higher than in the control group. At the same time, an additional profit was received in the amount of 9935,7 rubles per cow.

Diagnosis and treatment of acute purulent-catarrhal mastitis of cows in private subsidiary farms of the Kavalerovsky district of Primorsky Krai

One of the reasons for the decrease in dairy productivity of cows, sanitary and technological properties of milk, as well as premature culling of animals is mastitis.Despite the fact that extensive scientific research is being conducted around the world to develop measures to reduce the incidence of cows with mastitis, this problem continues to be one of the most urgent for dairy farming. The damage caused by this pathology consists of the loss of milk productivity, premature culling of animals, deterioration of milk quality, increas- ing treatment costs.In our work, we analyze data on the diagnosis and treatment of cows with acute purulent-catarrhal mastitis in personal subsidiary farms serviced by the FKGBI “Dalnegorskaya VSBBZh” Kavalerovskaya SBBBZH. To achieve this goal, the following tasks were set: 1. To study the methods for diagnosing acute purulent-catarrhal mastitis in cows in private farms serviced by the FKGBU “Dalnegorsk VSBBZh” Kavalerovskaya SBBBZH. 2. To study the methods of treatment of acute purulent-catarrhal mastitis in cows in private farms serviced by the FKGBU “Dalnegorsk VSBBZh” Kavalerovskaya SBBBZh.

Технологические свойства и качественный состав молока и молочной сыворотки коров в зависимости от влияния генотипов по генам каппа- и бета-казеина

Studies were carried out on 118 cows of black and white Holsteinized breed with certain genotypes according to beta- (CSN2) and kappa-casein (CSN3) genes. The aim of the study was to examine the qualitative composition and technological properties of milk and milk whey of black and white Holsteinized cows obtained by the rennet coagulation studies in the relationship with the genotypes for beta- and kappa-casein genes. The distribution of alleles for the CSN2 gene in the studied population: A1 – 0,424 and A2 – 0,576. The distribution of alleles for the CSN3 gene: A – 0,754 and B – 0,246. Among the cows studied, most of the animals (55,9 %) are carriers of the A1A2 genotype, 29,7 % of the A2A2 and 14,4 % of the A1A1. Carriers of the AA genotype were 57,6 % of the animals, 35,6 % were AB and only 6,8 % were BB. The whey-to-milk ratio showed reliable differences and trends among the groups of animals of different genotypes by CSN2 and CSN3 genes for the indices of MFF, MFP lactose content, dry matter and casein content, which indicates the influence of genotype on the properties of milk during technological processing. Single-factor analysis of variance showed a significant effect of CSN2 gene genotype on rennet clotting and MFP in milk. Also a significant effect of CSN3 gene has been shown on rennet coagulation of milk, milk yield, MFF, MFP, casein content; in this connection it is the most perspective factor for further study and inclusion in breeding programs in order to increase genetic potential of milk productivity and qualitative composition of milk most suitable for processing in the populations of black and white Holstein breed.

THE EFFECT OF CATTLE FEEDING RATION’ VITAMIN-AND-MINERAL ADDITIVES INFLUENCE ON MILK AND DAIRY PRODUCTS’ QUALITY

The dairy products’ quality and nutritional value determination, as well as their properties ability during storage preserving, on the raw milk technological characteristics are based. The raw milk technological properties formation’s great quality an important role plays the dairy cows’ nutrition. Highquality compound feed is the first and main element of a lot of livestock problems’ solving. Its uniformity and nutritional composition is livestock high quality products foundation. Their milk studies’ results obtained from cows’ black-and-white breed as "Bashkir" type from the SPK collective farm "Hero" enterprise are presented. This enterprise with technical means for compound feeds’ production and distribution is provided. The cows received "Megamix-Optilak" premix with ration, that compound feed as a components’ mixture in various dosages for its production was added. The "Megamix-Optilak" is a premix for lactating cows, that taking into account the dry matter consumption up to 22 kg per head per day was developed. During the feed mixtures’ preparation for the animals’ experimental group, a system of feed mixtures homogeneity’s optical assessment was used, that the premix uniform distribution for the mixer's modes operating and control optimization at the bulk feeds’ composition had ensured. Positive results regarding the milk quality and the extracted from it products (as the milk fat content till 1,75% and the fat yield during milk separation increasing were obtained, the protein content in 0,77% and the curd yield in 6,54% increasing), due to the feed high quality. The resulting product uniformity at the outlet at an optical system using was evaluated.

Therapeutic efficacy of complex treatment of cows with catarrhal mastitis

Mastitis in cows is widespread and causes great economic damage to agriculture. Every year, according to domestic and foreign authors, from 20 to 50% of highly productive cows get sick with mastitis during lactation. Mastitis milk leads to changes in the chemical composition of combined milk, as a result of which biochemical and microbiological processes are disturbed during its processing. The milk obtained from cows with mastitis does not coagulate well with rennet, is less thermosensitive, and productively valuable lactic acid bacteria do not develop in it. The damage caused by mastitis consists of a decrease in milk productivity, premature culling of animals, deterioration in the technological properties of milk, as well as the cost of diagnosis and treatment. The work was carried out in the livestock complex KH Agrofirm "Chokh" of the Gunibsky district of Dagestan Republic, on cows of the red steppe breed, aged from three to seven years, with mastitis, in the amount of 85 heads, divided into three groups: two experimental – 30 heads and one control – 25. The cows of the first experimental group were “intracisternally injected with the drug Laktiko, one syringe dispenser - 3 ml, in combination with the vitamin complex - Activiton, at a dose of 20 ml per head, for 3-4 days, the second - Gamaret, at a dose of 10 ml (1 syringe - dispenser), in combination with a probiotic - Gamavit, to control cows - Mastisan A, at a dose of 10 ml, once a day.The developed complex scheme for the treatment of catarrhal mastitis using the drug Laktiko in combination with Activiton, has a therapeutic efficacy 96.6%, the biochemical parameters in the first experimental group correspond to the “physiological norm on the 3rd day of treatment, the restoration of the productivity of the treated shares to 60 is day – 95%.

The quality of milk of cows-daughters of different bulls-producers and assessment of its suitability for processing

Relevance. The increase in the productive qualities of dairy cattle continues through the further use of purebred bulls-producers of the Holstein breed both of domestic and offoreign breeding, which invariably leads to an increase in the blood of the Holstein breed. Milk is not only a valuable food product, but also raw material for the dairy industry, and its use for the production of certain products is determined by its technological properties , so the study of them in a new genetic formation of dairy cattle in the Middle Urals zone has both scientific and practical interest.Methods. The research was carried out in one of the typical breeding reproducers for the breeding of Holstein black-and-white cattle of the Sverdlovsk region in the period 2018–2022. The evaluation included first-calf cows that completed the first lactation, obtained and grown on the farm. All cows are descended from breeding bulls Das, Sayan, De-Su, Gavano, Touareg, Marrs, Cassio, Bentley, who all 15 or more daughters. Qualitative indicators of milk— chemical composition, physico-chemical, technological properties and sanitary and hygienic indicators — were evaluated four times in three-fold repetition according to generally accepted methods and techniques in the dairy laboratory of the Ural State Agrarian University.Results. As a result of the conducted research, it was found that the milk of cows-daughters of different bulls-producers differs in chemical composition. In the milk of cows-daughters of bulls-producers Sayan and Cassio, the content of dry matter (DM), nonfat milk solids, protein, and milk sugar is higher. There was a significant superiority of these cows over their peers from other bulls in MJ in milk (Р ≤ 0.001). Milk obtained from cows-daughters of all bulls-producers corresponds to the highest grade. Differences in the technological properties of milk, namely in cheese suitability, were revealed, despite the fact that it was all attributed to the second type, the most suitable for the manufacture of cheeses. 

Characterization of the genetic polymorphism linked to the β-casein A1/A2 alleles using different molecular and biochemical methods.

The 2 major subvariants of β-casein (A1 and A2), coded by CSN2 gene, have received great interest in the last decade both from the scientific community and the dairy sector due to their influence on milk quality. The consumption of the A1 variant, compared with the A2 variant, has a potential negative effect on human health after its digestion but, at the same time, its presence improves the milk technological properties. The aim of the present study was to compare the best method in terms of time required, costs, and technical engagement for the identification of β-casein A1 and A2 variants (homozygous and heterozygous animals) in milk to offer a reliable service for large-scale screening studies. Two allele-specific PCR procedures, namely RFLP-PCR and amplification refractory mutation system (ARMS-PCR), and one biochemical technique (HPLC) were evaluated and validated through sequencing. Manual and automated DNA extraction protocols from milk somatic cells were also compared. Automated DNA extraction provided better yield and purity. Chromatographic analysis was the most informative and the cheapest method but unsuitable for large-scale studies due to lengthy procedures (45 min per sample). Both allele-specific PCR techniques proved to be fast and reliable for differentiating between A1 and A2 variants but more expensive than HPLC analysis. Specifically, RFLP-PCR was the most expensive and labor-demanding among the evaluated techniques, whereas ARMS-PCR was the fastest while also requiring less technical expertise. Overall, automated extraction of DNA from milk matrix combined with ARMS-PCR is the most suitable technique to provide genetic characterization of the CSN2 gene on a large scale.

The genotypic profile of milk proteins in Holstein cows raised in South of Brazil

Genotyping in dairy cattle allows knowing the alleles and genotypes associated with milk proteins that affect yield and milk quality. This study aimed to verify the genotype profile for κ-casein I and II (κ-CN), α-s1-casein (α-CN) and β-lactoglobulin (β-LG), for Holstein cows raised in southern Brazil, where there is no scientific evidence on the presence of these alleles in dairy herds. Hair follicles samples from each animal were used for DNA extraction and genotyping. We calculated the allelic and genotypic frequencies for four types of milk protein variants in the population, and a chi-square test was employed to see whether the population of animals used was in Hardy-Weinberg equilibrium. Allele A and AA genotype showed the highest frequency for both κ-CN (56.77 to 80.36%). For α-s1-CN and β-LG, the B allele was the most frequent, as BB (80.26%) and AB (47.15%), respectively. Due to the presence of alleles associated with protein levels in milk, we concluded that these herd cows present milk technological properties interesting to produce dairy products.

КАЧЕСТВО ПРОСТОКВАШИ В ЗАВИСИМОСТИ ОТ ПОРОДЫ КРУПНОГО РОГАТОГО СКОТА

The aim of the work was to conduct a comparative assessment of the quality of yogurt made from milk of cows of different breeds. The milk of the black-and-white breed of cows was more acidic, less fatty and with a lower content of skimmed milk residue and was fermented longer than the milk of the Simmental breed cows. The curdled milk from the black-and–white breed was more liquid, and the Simmental milk was thicker. When the enzyme was added, the milk of the Sim-mental breed had the densest clot. In the curdled milk of a black-and-white breed with the addition of an enzyme, the clot was looser. Curdled milk from the Simmental breed of cows was the dens-est when using the enzyme. Curdled milk from the black-and-white breed contained more organic acids in terms of lactic acid. The content of organic acids without the use of the enzyme increased faster in the curdled milk of the black-and-white breed. The breed of cows has proved to be one of the main factors influencing the technological properties of milk and the quality of fermented milk products produced from it.

ВЛИЯНИЕ ПОРОДЫ КРУПНОГО РОГАТОГО СКОТА НА КАЧЕСТВО РЯЖЕНКИ

The aim of the work was to conduct a comparative assessment of the quality of fermented baked milk obtained from the milk of two different breeds of cows: Simmental and black-and-white. The research was conducted in the Lipetsk region. The milk of the Simmental breed was fatter, less dense, with less acidity, a large amount of protein and skimmed milk residue. The rennet sample of milk of both breeds was less than 15 minutes, which indicates good coagulability. According to the reductase test, the milk of both breeds is of satisfactory quality, belongs to Class 2 and con-tains from 500 thousand to 4 million. CFU of bacteria per 1 ml. The content of somatic cells in the milk of the Simmental breed of cattle exceeded the norm (no more than 500) by 83 thousand cells/ml. More dense, homogeneous and dense was the fermented baked milk of the Simmental breed. The fermented baked milk from black-and-white cows was more acidic, and after 4 days of storage at a temperature of +4 oC, this trend persisted, while it also became more liquid. The ap-pearance of rod-shaped pathogenic bacteria was not detected in the fermented milk from the milk of both breeds of cows. The shelf life of fermented baked milk from both breeds of cows at a tem-perature of + 4 oC was 14 days. It is established that the breed of cows has shown itself to be the most important factor in influencing the technological properties of milk and the quality of the fermented milk product produced from it - ryazhenka.

The influence of different genotypes of kappa-casein and beta-lactoglobulin on the productivity of cows of Ayrshire, Holstein and Yaroslavl breeds

Under the conditions of intensification of dairy cattle breeding, genetic markers of protein-milk content, namely allelic variants of kappa-casein and beta-lactoglobulin, are increasingly used. They are established by the method of DNA testing on blood samples of breeding animals. This method is also being introduced in our country, which is especially important when selecting breeding sires for the artificial insemination network. The purpose of the research was to study the quality indicators of milk of cows bred in the region of breeds (Ayrshire, Holstein, Yaroslavl), and the protein-milk product produced from it as cottage cheese, depending on the influence of the genotype. The research has been carried out in CJSC “Agrofirma “Pakhma” in the Yaroslavl region. The object of research was cows of Ayrshire, Holstein and Yaroslavl breeds. The sample included 99 cows, including 36 animals of Ayrshire breed, 33 Holstein and 30 Yaroslavl breed. A comparative comprehensive evaluation of the dairy productivity of cows of Ayrshire, Holstein and Yaroslavl breeds under the conditions in one herd using DNA testing has been carried out, for the entire productive period of economic use, the realization of the genetic potential has been traced. For the first time in the Yaroslavl region DNA testing of Ayrshire cows was carried out and new data on the polymorphism of the CSN3 and LGB genes in Holstein and Yaroslavl cows were obtained. The association of CSN3, LGB genotypes and complex genotypes with milk productivity and technological properties of milk has been investigated. The yield and quality of cottage cheese from the milk of cows of different breeds in association with CSN3 genotypes have been studied. As a result of studying the quality indicators of milk of cows of different breeds and the protein-milk product produced from it as cottage cheese, depending on the influence of the genotype. It has been found that cows of different breeds and different genotypes had significant differences in the quality of milk and cottage cheese produced from it, which must be taken into account when conducting breeding work with these breeds.

Impact of genomic selection on health improvement of high-yielding cows

The use of selection in dairy cattle breeding, focused for many decades on increasing milk productivity and technological properties of milk (fats and proteins), has led to the health problems of cows, including a decrease in the reproductive function, the prevalence of lameness, metritis, mastitis, infectious lesions of hooves, ketosis, milk fever and others (on average, from 30,0 % to 70,0 %). Calves, which are born by high-yielding cows in their early postnatal period, are characterized by a high mortality rate due to diarrhea (56,0 %) and respiratory diseases (47,0 %). The mortality of young animals and the forced culling of cows are global problems in the world of dairy farming. As a result, there is an interest in disease resistance breeding of dairy cattle, given that only healthy animals have an economic value, being effective and profitable. The purpose of this article was to provide some information on the global trends in the selection of dairy cattle. It is shown that genomic selection, which is originally used among bulls for their assessment and selection based on the productivity of offspring, is currently used to select female cattle by predicting their own further productivity. At the same time, the current direction of selection is a new group of economically significant breeding traits related, inter alia, to animal health, when all traits are assessed together (milk productivity, fat production, protein production, number of live calves produced, incidence of mastitis, lameness, metritis and other signs). The level of genomic selection's reliability is shown, which is 49,0 %, achieved as a result of developments begun in 2016 on the use of genomic selection, taking into account the indicated signs of health. The task is to improve the reliability of estimates for a wide range of phenotypic traits that contribute to the profitability resulting from keeping dairy cows throughout their productive life.